So, after taking some video of zooming into a treeline I had planned to freeze on a closeup of them, which would then start to fade to black except for the text which would remain the color of the actual trees. After some time looking at the various options I can't quite figure out how to get this to work. Here is a picture to help.
you can place your text layer above the trees layer and set it as an alpha matte for the trees. now the trees will only be visible inside the text layer. you can then place another copy of the trees to dissolve from full to transparent.
more about alpha mattes in after effects here:
Very cool looking, that's exactly what I was looking for. Thanks very much